1. Field of the Invention
The present invention relates to a structure formed on a printed circuit board (PCB) for detecting unavailable lines of the PCB, and more particularly to a structure that is able to provide detection of the difference of the lines.
2. Description of Related Art
In general, the xe2x80x9cTest Couponxe2x80x9d process is used to detect unavailability of lines of the circuit unit of a PCB, that is, the designer is able to control a situation forming the lines by a microsectioning detecting technique.
With reference to FIG. 10, a PCB has a base board (70) and multiple circuit units (71) formed thereon. A first space (701) is prepared on periphery of the base board (70), which is used for retention by machines in manufacturing processes. When forming the circuit units (71) on the PCB, multiple second spaces (711) are respectively prepared on periphery of each circuit unit (71), which is used to separate the adjacent circuit units (71) to become many circuit boards (70) by a Break-away panel technique. The first space (701) of the periphery of the base board (70) is larger than the second spaces (701), thus the xe2x80x9cTest Couponxe2x80x9d process is executed on first space (701) of the periphery of the circuit units (71).
With reference to FIG. 11, a detecting structure (72) includes detecting lines and at least one via (not shown) connected multiple detecting lines (not shown). The detecting structure (72) is formed on the first space (701). The detecting lines (not shown) of the detecting structure (72) and the lines (not shown) of the circuit units (71) are formed at the same time on the base board (70). Therefore, the quality of the detecting lines is equal to the quality of the lines of the circuit units (71). After forming the detecting structure (72), detecting the situation of the detecting lines includes the following steps:
Firstly, sawing the detecting lines together with the via (not shown) connected to the detecting lines whereby the connection of the via and the detecting lines is checked. In order to obtain a higher correction of the detecting result, after sawing the detecting lines, multiple grinding processes are executed until the center of the via appears. Therefore, the situation of the detecting lines and via is detected according to observe whether the via is connected to the detecting lines. However, the detecting structure (72) formed on the first space (701) is farther than that formed on the second space (711) of the periphery of the circuit units (71), therefore detecting sawing section of the detecting lines is not able to completely control the situation of the lines of the circuit units (71).
As per the above description, there are many complex processes such as sawing, grinding, etc for detecting the situation of the testing lines and via. Especially, after the sawing process, the sawn section has only one direction. But the unavailable lines are able to be formed in other directions without being sawn, so that the detecting result is not exactly correct. Therefore, if the detecting result is unavailable, the whole circuit units formed on the same base board are useless, and thus the manufacturing cost is unnecessarily high.
To overcome the shortcomings, the present invention provides a detecting structure for a detecting unavailability of the circuits formed on a PCB to mitigate and obviate the aforementioned problems.
The objective of the present invention is able to provide a structure for detecting the exact unavailable lines of the lines of a PCB, and furthermore, to avoid using complex processes to check whether the lines are formed on the correct position.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.